The River Gwaun (Welsh: Afon Gwaun, "Gwaun" meaning 'marsh, moor') is a river in Pembrokeshire, West Wales, which flows west to the sea at Fishguard (Welsh: Abergwaun - 'mouth of the Gwaun'). The Gwaun rises in the Pembrokeshire Coast National Park on the northern slopes of Foel Eryr in the Preseli Hills, to the east of Pontfaen hamlet. The river is a slowly meandering stream passing through marshy, wet woodland with alder trees, water meadows and flood plains. Its river valley is deep and secluded through the Gwaun Valley, and passes through Pontfaen and Llanychaer to the sea at Lower Fishguard Bay.